It is often desirable to use goggles or a protective eye-shield for protecting one's vision when engaged in any number of activities or occupations such as outdoor winter sports, skiing, hiking, sledding, tubing, mountaineering, ice climbing, snowboarding, snowmobiling, paintballing, swimming, scuba diving, snorkeling, skydiving, hazardous activities requiring safety eye protection, industrial use, target shooting, police work, tactical operations, riot control, corrections or military use. Additionally, it is also often necessary to use goggles or eye-shields in environmental conditions which contribute to condensation build-up on the eye-shield, causing fogging and vision impairment. In this and similar environments, where the temperature of an eye-shield has dropped below a dew-point temperature, fogging can occur, obscuring the vision of a user, and possibly contributing to a hazardous environment.
A common characteristic of portable eye-shield devices is the fact that they are light weight enough to be carried on a user's body, e.g., worn on a user's head. Examples of fog-prone sport goggles intended for use during winter activities, have included goggles for downhill skiing, cross-country skiing, snowboarding, snowmobiling, sledding, tubing, mountaineering, ice climbing and the like, and are widely known and widely utilized by sports enthusiasts and others whose duties or activities require them to be outside in snowy and other inclement cold weather conditions. Examples of fog-prone dive masks have included eye and nose masks independent of a breathing apparatus as well as full-face masks in which the breathing apparatus is integrated into the mask. Examples of fog-prone eye-protecting shields have included a face shield that a doctor or dentist would wear to prevent pathogens from getting into the user's mouth or eyes, or a transparent face shield portion of a motorcycle helmet. Fogging that impairs vision is a common problem with such goggles, dive masks and eye-protecting shields.
Anti-fog sport goggles, dive masks and other highly portable transparent anti-fog eye-protecting shields use batteries not only to power these devices but also to heat the devices to prevent fogging of an eye-shield or viewing screen. Lithium-Ion batteries have been used in the powering of such heated eye-shields. A known issue with these Lithium-Ion batteries is the fact that, as their charge decreases over time in use, the voltage output they provide also decreases over time in use. Thus, with conventional lithium-ion battery-powered devices, there has developed a need to regulate power applied as the battery has become depleted over time to provide consistent heating to the eye-shield to prevent fogging.
There have been various conductive apparatus devised for preventing condensation build-up on eye-shields. The purpose of these conductive apparatus has been to provide an eye-shield and viewing screen that may be maintained free of condensation so that the user would be able to enjoy unobstructed vision and viewing during various activities. Prior sports goggles have been primarily used in environments requiring a high degree of portability, that is, where a power source for powering the electronics for the device has been advantageously carried on a strap for the goggle itself as shown and described in co-pending U.S. Patent Application Ser. No. 61/563,738, by McCulloch, for Modular Anti-fog Goggle System. As a result, such systems have needed to be light weight.
While such battery-powered eye-shields, especially heating devices which consume extraordinary amounts of power from batteries, need to be judicious in the use of total power source, generally measured in amp-hours, to preserve power source life, it has also become important that the power circuitry of such systems provide even power, or customized power, distribution across an eye-shield, as well as a consistent level of power to the eye-shield. Thus, the ability to adjust the amount of current delivered to the eye-shield's resistive element, compensated for decreasing voltage as the battery charge is depleted, had also become desirable.
Responsive to these concerns there has been provided U.S. Pat. No. 8,566,962, for PWM Heating System for Eye-shield, to Cornelius (the “PWM Patent”), in part to allow application of different on-cycle PWM levels to an eye-shield, for example depending upon the heating requirements of different portions of the eye-shield, and also to enable even and consistent heating, or alternatively custom heating in accordance with a profile, over the entire eye-shield.
The PWM Patent has proven useful to allow a user to adjust power consumption, to enable even distribution of power across a divided eye-shield and to maximize battery life in an eye-shield, but the limitation of Lithium-Ion battery depletion and correspondent voltage depletion had nevertheless remained a problem. Thus, it was recognized that, where there is sufficiently available battery power to perform heating operations on an eye-shield device, an appropriate amount of additionally available power would have been useful to make power supplied to the device more consistent throughout the depletion cycle of the battery.
Accordingly, another problem with powered eye-shields to prevent fogging has been that, as available power to heat the eye-shield has decreased as the battery has worn down, a chosen power setting has been less effective to produce consistent heating of the eye-shield. Thus, in the Battery Compensation System Using PWM patent application Ser. No. 14/046,969, to O'Malley and Cornelius, (the “Parent Application”) a system has been provided for monitoring voltage output from the battery over time, together with compensation in the PWM circuit, to increase the percentage on-time of the system in order to increase power supplied to the heater to provide consistent heating of the eye-shield over time despite partial depletion of the battery.
As the battery to an eye-shield has become depleted over a cycle of use, especially with lithium-ion-type batteries, the power generated has decreased, and this has led to inconsistent application of power to heat the eye-shield over the cycle of use. These problems have resulted in limited usefulness of heating of goggle eye-shields. Because of the irregular shape of eye-shields, these problems have existed whether one is considering resistive wire applications or resistive-film applications.
No prior art goggle has made use of their battery supplies to provide evenly distributed and consistent power to the device despite depletion of battery charge. There have been no known methods or systems disclosed in the prior art for balanced, even heating of a resistive element on an eye-shield, while compensating to provide consistent power to the eye-shield, despite partial battery depletion and to enable effective and efficient defogging of the eye-shield over an extended period of time. U.S. Pat. No. 4,868,929, to Curcio, for Electrically Heated Ski Goggles, comprises an eye-shield with embedded resistive wires operatively connected via a switching device to an external power source pack adapted to produce heating of the eye-shield for anti-fog purposes. U.S. Pat. No. 7,648,234, to Welchel et al., for Eyewear With Heating Elements, discloses use of nichrome and thin film heating elements used for heating an eye-shield and discloses use of a control mechanism for turning on and off the heat to the eye-shield. Neither discusses the foregoing power regulation, power conservation and power distribution concepts for an eye-shield. Neither discusses the use of PWM circuitry to provide even, or custom, power distribution, consistent and efficiently-regulated power to an eye-shield, despite charge depletion.
Manual switching the power on to an eye-shield when a user has experienced fogging conditions, and then later manually switching it off when the user has suspected the fogging has dissipated and heat has been no longer required, as would have been required in the prior art to maximize battery life and still seek fog dissipation, has not been, and would not be, an efficient way to consistently and efficiently overcome fog and condensation. This method has not been efficient for prior art eye-shields in part because while the eye-shield has used full power while it has been turned on, hot spots have been created in the irregularly-shaped lens eye-shield, and this has led to attempts to adjust for the hot spots and a consequential inefficient use of battery resources. Additionally, it has been difficult to gauge power requirements for a fog-proof eye-shield, since users haven't been able to gauge the relative humidity and temperature within their goggle enclosures, and since existing fog has taken more power to dissipate, while maintaining an existing fog-free lens in a fog-free state has required a lesser application of power. Accordingly, users haven't known precisely when to turn off power to the heater, so at best, the user has had to guess when was an appropriate time to turn off the power. This, in turn has led to fogging if the device has been turned off too early, or on the other hand, has led to hot spots and wasted power usage if the device has been left on too long. When a user has been involved and concentrating on an activity at hand, it often has not been convenient to have to turn on, or to turn off, the power to heat the eye-shield. Further, users have forgotten, indeed may even be prone to have forgotten, to turn off the power to their goggle devices, thus unduly and quickly depleting valuable power resources. Thus, manual switching on and off of devices as needed to prevent condensation has not allowed for precise fog dissipation, has not enabled a judicious use of power, nor has it allowed for intermediate power usage which would have been useful to sufficiently curtail fogging while still conserving battery life.
Thus, there has been discovered a need to provide a power-saving method for defogging a goggle, or eye-shield, which provides adequate power to meet the requirements of defogging the eye-shield under varying conditions, and which also maintains the eye-shield free of condensation, while striving in an overall method and system to conserve battery life. Similarly, there has been discovered a further need for a method to control an anti-fogging device on an eye-shield that would provide enough power to dissipate fog and condensation quickly, that would curtail future fogging and that would provide even, consistent heating despite battery depletion over time in use, and yet still strive to conserve battery life by providing for a judicious use of readily available, light weight, power resources.